The many Voice over Internet Protocol (VoIP) clients currently on the market, such as SKYPE®, have changed the way we think about communication and keeping in touch with loved ones over great distances. The advent and widespread use of VoIP clients on personal computers has increased the popularity of VoIP services. As little as ten years ago, most people had to rely on expensive mobile and Public Switched Telephone Networks (PSTN) to carry their voice over short and long distances. Today, however, almost everyone seems to be using VoIP technology in one way or another. Instead of sending signals via a PSTN network, be it analog or digital, a VoIP application usually uses Session Initiation Protocol (SIP) to create data packets, and transmits the data packets using the same network used for email and web browsing.
By using data packets, the technology can be used to carry more than the standard mono voice the old telephone carries: VoIP can carry text, images, live video and high quality stereo sound as well as ‘screen sharing’, depending on the speed and reliability of the internet connection. With the continually expanding broadband users market, more people are able to use VoIP without investing in a separate physical connection or contracts.
These communication systems allow the user of mobile devices such as personal computers to communicate across a packet-based computer network such as the Internet in much the same way that they once used the traditional phone network. Cellular IP phones configured with a VoIP client allow the IP phone user to enjoy the same free VoIP service as a personal computer user. This, however, requires a special Wi-Fi phone, or a dual-system phone with a VoIP client installed. VoIP systems are beneficial to the user as they are often of significantly lower cost than conventional fixed line or mobile networks. This may particularly be the case for long-distance and international communication, where traditional phone calls can be substantially more expensive. To use a VoIP system, the user installs and executes client software on their computer, phone, or other mobile device. The client software coordinates with a server to provide the VoIP connections as well as other functions such as registration and authentication.
In addition to voice communication, the client may also provide further features such as video calling, instant messaging (IM), Short Message Service (SMS) messaging, file transfer and voicemail. The Short Message Peer-to-Peer (SMPP) protocol is used for SMS messaging. The SMPP protocol is a telecommunications industry protocol for exchanging SMS messages between SMS peer entities such as short message centers and/or external short messaging entities. The most commonly used versions of SMPP are v3.3, which supports both transmission and reception of SIMS messages on distinct connections and is the most widely supported standard, and v3.4, which adds transceiver support, allowing both transmission and reception tasks to be performed on a single connection.
Although they are much more versatile than traditional PSTN communications, currently existent VoIP communication systems have been criticized by many for lack of user-friendly features, such a caller identification and a call back feature allowing the recipient of a call that comes from the VoIP system to recognize a mobile number of a caller to call the mobile number of the caller back. The same features are lacking for sending and receiving SMS messages via VoIP communication networks. This inability to see the caller identification of VoIP callers and SMS message originators in turn exposes the recipient to the risk of fraud or unwanted solicitations.
In addition, emergency services have strongly objected to the use of VoIP for emergency calls due to the inability to locate the caller within a reasonable area. For example, a user connected to the office virtual private network would appear to be in the server building instead of the real location. This means that a person who places a VoIP emergency call and subsequently cannot speak to the emergency service provider will be very unlikely to receive assistance sufficiently quickly to prevent injury and death. In contrast, emergency calls transmitted via wired telephone networks and to some extent mobile phone networks generally enable emergency workers to determine the location from which the emergency call originated rapidly, either by looking up the address of the land-line connection in the former case, or the cell tower or Global Positioning System (GPS) location in the latter. It is not difficult to imagine scenarios in which the victim of a heart attack or similar emergency would find him or herself unable to speak after placing a call, so this deficiency of VoIP telephone service is potentially a matter of life and death.